Apparatus for testing hardness of firm bodies



April 20 1926.

` C. E. DAHLQVIST APPARATUS FOR TESTING HARDNESS OF lBODIES Filed Feb.25, 1925 Patented Apr. 20, 1926. i

UNITED STATES assiste CARL EDVARD DAHLevrsfr, on srooxnoriiu, swnnnri.

APPAaArUs Foa 'rns'riive Hannunss or Finir BODIES. A

,y vApplication filed February 26, 1923. Serial No. 621,388.

fo all whom; it may concern.

Be 1t known that I, CARL EnvARn DAHL- Qvrs'r, engineer, a subJect oftheKingl of Swed-en, and resident of Stockholm, in the county of Stockholm,Sweden, have invented certain new and useful Improvements in ApparatusVfor Testingl Hardness of Firm Bodies, of which the following is aspecification. e Thel present' invention relates to implements fortesting `the degree ofhardness or resistance of solid materials, suchlasmetals, etc.; and it embodies certainy improvements whereby thespring which operates the impact element may be cocked or set'withoutpressing the implement against the object tobe` tested, and wherebyglancing or ineffective strokes of the impact element may be avoided,all as hereinafter fully described.

One form rof the invention is illustrated, by wav of example, in theaccompanying drawing, wherein';-` v t Figure l is a longitudinal sectionof the completeimplement; i f Y Fig. k2 is a plan viewl of a lockfnutwhich is used on the impact element;

Fig. 3 is a part-sectional side elevation of a device for cooking theoperating spring;

Figa 'ifs a bottom plan'view of an attachment for guiding and holdingthe impact element; 'f iV FigL 5 isalongitudinal section thereof on lineA-A, Fig. 4; and y Fig., 6 is a top plan view of said attachment;

Referring 'more particularl to the drawing, 2 indicates thetubular sellor case of the implement, and 1 a cap or cover removably threadedinto thei1p.per endl of the-case andv provided withaj `central opening27. The lowerend wall 19 ofthe case is made with a perfectly -flat orplane outer face, for a purpose subsequently explained, and like- Wisehas` an opening at its center. Withinthe case 2, there is-slidablyarranged an impact element 16 inthe form of a rod or plunger having itsupper portion threaded, as shown, and provided. immediately abovesuchthreaded portionwith a transverse `opening '3; thev 'lower end of therod terminatin in a rounded'or-y pointed member 18 whic i is disposed.exactly` in line with the opening in the bottom wall 19 of the case.lock-nut 4 is mounted on the threaded'. upper portion of the rod and issplit radiallyat 5 (Fig. 2) ,the two legs produced Aby the Vsplitbeingprovided with threadedscrew-holes to receive a clamping vscrew orbolt 6 which, when tightened, willv serve to lock the nut in adjustedposition upon the rod, as will be understood.

The impact rod is adapted to slide longitudinally within its case,and'is guided during such movement by upper `and lower bear-V ings 7 and20, the latter of which consists ymerely of4 a transverse partitionhaving a central opening. vThe upper bearing is in@ the form of asleeve, the bore of which is of larger diameter than the rod to enable'said rod to slide freely therethrough.` The upper portionofthe sleeveis enlarged to rform a head, and this head is split by twodiametrically-intersecting cuts 8 which thus divide it into foul" equalsectors 9 (Figs. 5 and 6) the confronting side walls of the sectorsbeing formed yconjointly with tapering screwholes for the reception oftapered expanding screws 10'carryingnuts. 11 at their lower Y ends to`rhold them against displacement.

- i The peripheral'wall of the sleeve head is threaded for engagementwith an internallyf threaded portionofthewallv of the case lo-v cated avsuitable distance below the upper end thereof, so that it is thuspossible toattach the sleeve to the case wall at any desired pointwithin thefrange of the afore-y saidV threaded portion. The screws l0can then be tightened to expand the head, whereupon the sleeve will beiirmly locked in place. So positionechfthe'impact rod 16 can movekfreelyin opposite directions through p the sleeve, its downward movement beingrlimited by the contact of nut l with the upper face of the sleeve. f

The portion of the bore ofthe sleeve which extends through the sleevehead, however, is y made slightly` smaller than'the boreof the sleeveproper (see Fig. 5), and this portion of the bore is enlarged, ofcourse, when the expanding screws l0 are tightened, so that the rod canthen pass freely through it. But when said screws are loosened, then thesectors 9 forming the 'head will ,tend to come together, thuscontracting the aforesaid bore portion, with the result that the sleeveis firmly clampedto the rod. -Hence, inassembling the parts, the sleevehead is `rst expanded to enable it to heA fitted on the rod,

and then contracted to lock the twoparts together, after which the rodand sleeve are inserted into the case and the head jthereafter locked inadjusted engagement with -dinal series of stops the threaded portion ofthe case wall, thus releasing the rod from the sleeve head and leavingit -tree to move axially in either direction.

The working stroke of the redis e'iifected by means oi-an operatingspring 13, here shown as coiled aroundthe central portion of the rod.One end of this spring bears upon an annular shoulder or collar 17'formed upon or otherwise rigid-ly secured to the rod and provided withafbeveled edge,

while the other or upper end fits in a spiral groove 12 (Fig. 5) formedin the outer surface ot' the sleeve and is fastened in place therein bymeans of a. set-screw 14- and washer 15;the locking of said sleeve tothe rod preventing the upper end of the spring from turning or twistingon the sleeve when the latter is being screwed into the threaded part ofthee-ase.

As the sleeve is normally locked to the case, and as the spring 13 is ofthe-expansibletype, the tendency oi said spring` is to move the roddownward or outward. To provide the torce necessary for the workingstroke of the rod, the spring' is cocked or compressed to an extentdepending upon the character and thickness of the material to be tested.A preferred form of device for effecting this cooking or contractingaction is shown in Fig. 3 and comprises a stemor bar 4provided along oneside with a llongitu- 26, marked I to X, and of such a. size and shapethat it vcan pass freely through the opening in the bottom wall 1910i?the case; An enlargement or base is provided on the lower endo'l thismember, and its upper end has aseat or CII depression 25 formed thereinto receive the terminal 1S of the impact rod, so that after the saidparts 18 and 25 have been engaged, the stem or bar can be forced inwardthrough the aforesaid opening into the interior ot the case. therebymoving` the rod backward and contracting the spring until the desiredstop 26 reaches the case opening. Oneway ot doing this, is to rest thedevice 'upon a suitable support by means of its base, thenv position theimplement directly thereabove, with the parts 18 and 25 engaged, andthen pressv downwardly upon the caseunt-il the stem 'ot the device hasmoved in ard to the required extent.

Y'oretain the parts in cocked position, a detent lever2l is utilizedwhich also serves to uncock or release them. rllhis lever is disposedlongitudinally and exteriorly of the case.l and is tulcrumedintermediate its ends in a bracket on said case, asrepresented inFig. 1. The lower arm ol" the lever is formed along its inneredge with aseries ot ratchet teeth 2l, marked I to X tol agree with the marking` ofthe stops 2S; and immedi ateljv below the lowest tooth, which is markedl', there is a lateral projection or lug serving to indicate the normalposition of the impact rod and marked 0. The portion of the caseimmediately opposite the toothed portion of the lever is formed with alongitudinal slot or opening, through which the said portion oi" thelever projects, due to the action of a spring 23 interposed between thecase and the upper arm of the .lever and, hence` situated above theulcruin oit the latter. Both the teeth 2l and the lim- 22 are designedto coact with the collar or shoulder 17 on the rod; and in the normal orzero position of the rod, which is illustrated in Fig. 1, the lugengages the under surface ot'said collar, and said ksurface is disposedalmost, butnot quite, in contact with the upper face. of the partition20. The teeth 21 slant upward, as shown, so as to oder no interferenceto the inward or upward movement or" the rod, the lever vibratingbackward and forward -in its slot during such movement and engagingunder the collar'l as the latter passes eachy tooth, sothat the .rodwill thus be automatically locked against return movement. Inwardmovement oit the upper arm of the lever, however, will immedi atelyrelease the lever 'from the rod collar, and the rod will thereuponl beinstantly moved outward or downward by the expansion of the operatingspring 13.

ln order to initially; balance the spring 13, one end of a beam (notshown) may be inserted through the hole 27 in the top of the case andhooked into the opening 3' in the upper end of the rod, and the requirednumber ott Vweights are suspended from the other end ot the beam,whereupon the compression of the spring is measured. Y

The operation of the implement is bclieved to be apparent fromvtheforegoing and, hence, to require no special explanation. It will beobserved, however, that the operatlll ing spring is cocked withoutrequiring-the e Yimplement to be pressed against the material to betested, but that, instead, this action is eiected by means of the stemdevice illustrated in Fig.4 3. Consequently, it is possible vto adjustthe tension lof the springend to set the impact rod with a great deal ofnicety, as well as to position the flat end face 19 Aot the casesquarely against the surface of thematerial.k This disposition oi' theaforesaid end face 19 places the axis of the rod truly perpendicular tothe said surface, and the rod is accordinglyV compelled to strikev adirect blow thereagainst, all danger of a glancing or misdirected blowthusbeing avoided. Furthermore, it is to be noted that the operating'spring acts 'directly on the'impact rod, and thatthelatter-itselfstrikes directly against thc material, so that there is nowaste eti'ort such as is necessarily present when the operating orimpact element and the element which strikes the work are structurallyseparate Y bined locking and releasing lever LA not only performs thefuction speciied, but also serves to give noticefwhen, by reasonfol-Wear on or displacement ofany of they partsv within the case, areadjustment of the impact rod is necessary. v As has been explained,the rod' is .normally heldin z ero position, represented in Fig., l,invvhich the lug 22 on the lever catches under the collar or shoulder17. This position it vassumes automatically immediately vfollowing itsWorking stroke, due ofcourse to thev recoiling of the operating springafter-its sudden expansion. If, now, fo'r'the reasons stated, suchautomatic engagement doesnot take place that fact is at once indicatedand'` the need for further adjustment isapparent.

I claim as my invention 1. A resistance-testing implement, com` prisinga ease havingone endadapted to be positioned directly againstthefsurf'ace of the material being tested; an impact element-housedWithin the case vand movable axially outward throughy said end to strikeagainst said material; an operating spring 'for said element; andreleasable means for holding said element in any selected one of aseriesof dil'erent, definite retracted positions in sai-d case with itsoperating spring cocked. f

2. A resistance-testing implement, com-- prising a case having one endadapted to be positioned directly against the surface ofV the materialbeing. tested; an impact rod housed Within the case`and movable axiallyoutward through said end to strike against said material; an operatingspring' for the impact rod, said rod being movable inward of said case,against the action of saidl spring, to different predetermined eX-tents; and means, operable at will, for holding and subsequentlyreleasing said rod in and from any selected retracted position.

3. A resistance-testing implement, according to claim l, in which thereleasable holding means comprise a member having a set of ratchet teethfor selective engagement with the impact element.

4. A resistance-testing implement, according to claim 1, in which thereleasable holding means comprise a member having a set of ratchet teethfor selective engagement With a shoulder on the impact element, theratchet teeth and the edge of the shoulder heilig inclined or beveled ina ldirection toy enable the-free .inward movement of saidtain suchengagement and k.to hold the other arm of the lever in releasingoperation.

6. A resistance-testing implement, iconi-4 prising a tubular case havinga` bottom end position to eff-ect the Wall Vprovided With a centralopening; an

axially-movable impact element housed Within said case; an operatingspring for moving said elementoutward through said opening to strike"against the material being tested; and releasalole meansfor 'retainingsaid element in retracted position in said case, said end Wall having aflat outer face which -is adapted to restsquarely against the surface'ot'said material and to Which the axis of the impact element isperpendicular. f* s i 7. A resistance-testing implement, comprising atubular case; an axially-movable impact element therein; ytixed andmovable guides in saidv case through which said element passes, themovableV guide having means for releasably locking it to Lthe cas'c andtothe impact element; a spring-for efffecting the Working stroke ofsaid' element; and releasable means for holding said element inretracted position with its operatings'pring cocked.`

, 8. A resistance-testing implement, `coniyprising a tubular case; anaxially-movable `impact element therein; fixed and movable guides insaid case through `which said element passes, the movablev guide havingmeans for locking it alternatively to the case or to the impact elementand simultaneously unlocking it from said element or from said case; aspring for electing thel Working stroke of said element; and releasablemeans for holding said element in retracted position with its operatingspring cocked.

- 9. A resistance-testing implement, according to claim 7, in which thereleasable locking means comprise a sleeve having ahead which isformedwitli a plurality of inter-` vil() ing a bottom end member formedwith a central opening, an impact element movable, outward through saidopening, an operating spring for said element, and relcasahle means forlocking said element in retracted position; of a member engageable withthe outer end of the impact element and adapted to be forced inwardthrough said opening to retract said element and tension its oper-`ating spring. 11. The combination, with a resistancetesting implementcomprising a. case hating a bottom end member formed with a centralopening, an impact element movable outward through said opening, anoperating spring for said element, and releasable means tor locking saidelement in retracted position; of a member engageable with the outer endof the impact element and adapted to he forced inward through saidopening to retract said element and tension its operating spring, saidmember being provided along one side with a series of indicatingdeviceey which correspond to'dit'ferent predetermined tensions of saidspring and which are adapted to coact with the edge ot said opening- Y12. A resistance-testing in'iplenient, coinprising a case; anaxially-movable impact element housed'therein; an operating spring forlsaid element; and` relcasable means for lockingksaid elementselectively. in any one of a plurality of different definite positions,said locking means and impact element constituting companion parts, oneof. which-is provided with a setrof ratchet teeth for intcrchangeableengagement with a projection on the other part.

13. A resistance-testing in'iplenient, coni. prising a case; anaxially-movable impact element housed therein; an operating spring forsaid element; and a lever for releasably locking Said element in anyselected one ot a plurality ot' different predetermined positions, 'saidlever having a series ot ratchet teeth for interchangeable engagementwith a projection on said element and aisoy having a lug at the foot ofthe series ot teeth to normally engage said projection.

14. The' combination, with a resistancetesting implement comprising acase having a bottoml endmember formed with a central opening, an impactelement movable ont.- ward through said opening, an opeiatingspring forsaid element, and a lever having a set of ratchet teeth forinterchangeable engagement with a projection on said element toreleasably lock the latter in any selecte(l one of a plurality ofkdifferent retracted positions; of a member engageable with the outerend of the impact element and adapted l to be forced inward through saidopeningl to retract said element, said n'ieinber being provided alongone side with a longitudinal series of indicating devices for coactionwith the edge of the opening, said devices cor responding with saidratchet teeth in number and spacing. Y

In testimony whereof I have hereunto set my name this ninth day ofJanuary 1923.

CARL EDVARD DAHLQVI ST.

